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Gratuitous ARP is wrong #225

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hannesm opened this Issue Jul 12, 2016 · 2 comments

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@hannesm @yomimono
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hannesm commented Jul 12, 2016 •
edited

RFC 5227, section 3 (https://tools.ietf.org/html/rfc5227#section-3) says it should be a ARP request with spa = tpa (mirage-tcpip uses a ARP reply with tpa = broadcast). Section 3 also makes it clear why an ARP reply is a bad idea. Related to mato/docker-unikernel-runner#1 (setting arp_accept (somewhere in proc on linux) to the bridge and sending an ARP request solves the issue (just verified with @mato)).

Discovered while reimplementing ARP (https://github.com/hannesm/arp - https://hannes.nqsb.io/Posts/ARP)

@hannesm hannesm referenced this issue Jul 12, 2016

Closed

Network delays due to random MAC address use #1

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yomimono commented Jul 12, 2016

Thanks for the report - we're indeed doing it pretty wrong. I'll fix this up.
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hannesm commented Jul 12, 2016

I'd guess a branch off 2.8.0 release with having only this fixed (and a 2.8.1 release) would make people, instead of waiting till master is in a state to be released (which requires new mirage-types release)....

yomimono added a commit to yomimono/mirage-tcpip that referenced this issue Jul 15, 2016

@yomimono
process incoming ARPs & construct GARPs per RFC 826. 
Per RFC 826, don't look at the `op` field of the packet before deciding
whether to use it to update the cache.  Also, construct gratuitous ARP
packets as Requests, not Replies, and set the destination host address
to the source host address.  This fixes mirage#225.
Loading status checks…
e04e9bf

yomimono added a commit to yomimono/mirage-tcpip that referenced this issue Jul 15, 2016

@yomimono
process incoming ARPs & construct GARPs per RFC 826. 
Per RFC 826, don't look at the `op` field of the packet before deciding
whether to use it to update the cache.  Also, construct gratuitous ARP
packets as Requests, not Replies, and set the destination host address
to the source host address.  This fixes mirage#225.
Loading status checks…
542bba7

yomimono added a commit to yomimono/mirage-tcpip that referenced this issue Jul 15, 2016

@yomimono
process incoming ARPs & construct GARPs per RFC 826. 
Per RFC 826, don't look at the `op` field of the packet before deciding
whether to use it to update the cache.  Also, construct gratuitous ARP
packets as Requests, not Replies, and set the destination host address
to the source host address.  This fixes mirage#225.
Loading status checks…
e66dc0e

@yomimono yomimono referenced this issue Jul 15, 2016

Merged

process incoming ARPs & construct GARPs per RFC 826. #227

@yomimono yomimono closed this in #227 Jul 22, 2016

mato added a commit to mato/docker-unikernel-runner that referenced this issue Aug 10, 2016

@mato
Switch to mirage-dev remote for unikernel containers 
This pulls in the GARP fix from mirage/mirage-tcpip#225 which helps with
 #1, and no longer uses the solo5/opam-solo5 remote for Solo5.

Further net.ipv4.conf.docker0.arp_accept is set to 1 for Travis which
should make the tests run more reliably.
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9dfaeb7

samoht pushed a commit to samoht/mirage-tcpip that referenced this issue Apr 4, 2017

@yomimono
process incoming ARPs & construct GARPs per RFC 826. 
Per RFC 826, don't look at the `op` field of the packet before deciding
whether to use it to update the cache.  Also, construct gratuitous ARP
packets as Requests, not Replies, and set the destination host address
to the source host address.  This fixes mirage#225.
4ac81ba
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